Numerous process applications in industrial process plants require controlled or engineered pressure reductions to operate efficiently. One such facility wherein controlled pressure reductions are elemental for general operation and as well as for operating at peak efficiency are power generating stations. Modern power generating stations or power plants use steam turbines to generate power. In the so-called turbine bypass mode of such a generating plant, steam that is routed away from the turbine through a bypass loop and must be recovered or returned to water, such as occurs during turbine maintenance periods or shutdowns, where continued boiler operation is more economical than complete boiler shutdown or during normal plant startups and shutdowns. In turbine bypass mode, supplemental piping and valves that circumvent the steam turbine and redirect the steam to a recovery circuit are used to reclaim the steam for further use. Air-cooled condensers are often used to recover steam from the bypass loop and turbine-exhausted steam. An air-cooled condenser facilitates heat removal by forcing low temperature air across a heat exchanger in which the steam circulates. Air-cooled condensers, thus, condense saturated steam before it returns to the plant's feedwater pumps.
Because the bypass steam does not produce work through the turbine, its pressure and temperature is greater than the turbine-exhausted steam. In order to maintain the economy of smaller pipeline sizes, fluid pressure reduction devices, commonly referred to as spargers, are often used to allow the bypass steam to take a final pressure reduction into the condenser duct. Typical spargers are constructed of a hollow housing which receives the bypass steam and a multitude of ports along the hollow walls of the housing to provide fluid passageways to the exterior surface. Spargers operate by dividing the incoming fluid into progressively smaller, high velocity jets, whereby the sparger reduces the pressure of the oncoming bypass steam and vaporizes any residual spray water within acceptable limits prior to entering the air-cooled condenser.
Typical spargers require sufficient controlled flow area such that when installed, they extend a substantial distance into the condenser duct. However, such sparger devices have the unwanted effect of restricting steam flow past the spargers within the condenser duct. Further, the pressure of the reduced bypass steam is typically in the range of 30 to 150 psi, and during turbine shutdown, the pressure within the condenser duct is generally at partial vacuum. As the reduced bypass steam goes through typical sparger units and enters the condenser duct, the fluid pressure is lowered through the restrictive passageway of the sparger units and the potential energy in the fluid is subsequently converted to kinetic energy in the form of turbulent fluid motion. That turbulent fluid motion, in an air-cooled condenser system, can create undesired aerodynamic conditions, inducing physical vibration, and noise in significant magnitudes. To accomplish this energy reduction, the external volume of the typical sparger is necessarily increased. As known to those skilled in the art, the increased volume of the sparger can create substantial increases in condenser duct backpressure, which can be detrimental to turbine operation. There is a need for a sparger device that can substantially eliminate the lower frequency noises typically produced by interaction of sparger devices with the duct which can be harmful, i.e., damaging structural elements and unwanted vibration within the condenser duct, while also minimizing higher frequencies included through 8000 Hz as required for normal site permits without substantially increasing system backpressure.